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artful bodger
22nd November 2016, 08:34 PM
Wondering if anyone has the larger sized vicmarc 120 dovetail jaws kicking around that they don't really use? Looking for the 173, 198 , and 223mm types (expansion mode)

Mobyturns
24th November 2016, 07:40 AM
Going by the number of turners who still use standard 50mm jaws on some pretty large bowls and platters, I think your request may be a little optimistic. :wink:

lithro
24th November 2016, 03:49 PM
Is there a certain ratio or chart somewhere as to the sizes of jaw you should use?
I briefly searched for the g3, which is the only chuck i have so far, but i found nothing easily.
With the default jaws on a G3 at what point are they going to be ineffective?
Thanks
Lithro

artful bodger
24th November 2016, 07:39 PM
Going by the number of turners who still use standard 50mm jaws on some pretty large bowls and platters, I think your request may be a little optimistic. :wink:


Thank you for the encouragement Moby. My wanted to buy add a while ago did in fact eventually score me a set of 128mm jaws at a very nice price, so you never know.
I would be most interested to see some pictures of pretty large bowls and platters that have been made with the standard jaws, can only assume they have been made in the chuck expansion mode?. I am yet to see a pleasing design in the expansion mode but would really like to.

[ Quote=Is there a certain ratio or chart somewhere as to the sizes of jaw you should use?
I briefly searched for the g3, which is the only chuck i have so far, but i found nothing easily.
With the default jaws on a G3 at what point are they going to be ineffective?
Thanks
Lithro /Quote]

Yes Lithro, there is a chart that comes with the Vicmarc chucks. Although I am unfamiliar with the G3 type. Here is a pic of the chart, you will see it specifies each set of jaws in both expansion mode and clamp mode. You will also see there are lots of choices.
400432

pommyphil
25th November 2016, 09:43 AM
400464400465400466These three were handy.
Unfinished Cypress bowls from 420 to 310mm dia, done with 150mm jaws in expansion mode. The smallest one is an order, a working " Dough Bowl" that won't fall over.

Unstable bowls often look nice but if you can't chuck a few bananas in without it falling over it's a "Gallery" piece, "Art",unusable and purely ornamental.

chuck1
4th December 2016, 08:53 PM
Is there a certain ratio or chart somewhere as to the sizes of jaw you should use?
I briefly searched for the g3, which is the only chuck i have so far, but i found nothing easily.
With the default jaws on a G3 at what point are they going to be ineffective?
Thanks
Lithro

Teknatool nova have a book with all the jaws and recommendations of limits, dog's and don't. And I think you can download it.

Mobyturns
5th December 2016, 07:39 AM
I would be most interested to see some pictures of pretty large bowls and platters that have been made with the standard jaws, can only assume they have been made in the chuck expansion mode?.


I don't use the standard jaws on large bowls, however many turners create a larger tenon then use the jaws fully extended. That practice is not recommended as it stresses the scroll in the chuck and is an inefficient and not very secure method of holding a blank. Only the eight "corners" of the jaws are clamping the tenon, so the clamping force of the scroll chuck is concentrated on a very small area of the tenon, rather than the whole circumference of the tenon. That then causes other issues such as very localized crushing of the wood, which may also crush at different rates (different timber density) as the turner constantly nips up the jaws to keep the work secure.

lithro
5th December 2016, 09:52 AM
Thanks Chuck1 and Artfulbodger. Found it and trying to work out how quickly i will need to spend the dollars, but i did get some 75mm from the carbatec sale.

I understand G3 is entry level, but well made and functional. Will it become clear to me when i need to upgrade, because within the scope of my lathe i cant see it being necessary.

Thanks guys